1. Field of the Invention
The present invention relates to a cooling module and, more particularly, a piezoelectric air jet with an integrated heat dissipating module to augment cooling for electronic devices within a limited space.
2. Discussion of the Related Art
There is insufficient space for a convention cooling fan inside a smartphone-size computer. This is especially true for a smartphone-size computer that includes a high-power x86-type processor. To address this cooling issue, thermal management companies, such as SUNON in Taiwan, introduced “mighty mini-fans” which fit into such limited space. However, such “mini-fan” products do not generate enough air flow to cool down the high-power processor effectively. Recently, GE Global Research introduced a piezoelectric “dual cool jets” (DCJ) device and Murata in Japan introduced a “microblower”, which acts as a conventional fan. These devices are much thinner.
The piezoelectric phenomenon was first demonstrated in the 1880s. Using the piezoelectric phenomenon in applications of air flow generation began much later. In fact, it is only recently that more piezoelectric products are developed specifically for the electronics cooling market. The inverse of the piezoelectric phenomenon (“the inverse piezo effect”)—i.e., stress generation in response to an applied electric field—provides the basis for a new generation of piezo-fans. In a piezo-fan, the inverse piezo effect generates an air flow. Typically, a metal or plastic blade is bonded to a layer of the piezoelectric material (“piezo-layer”). When an electric field is applied to the piezo-layer, the ions in the piezo-layer become aligned, and deform the piezo layer. If the applied electric field is an alternating field, the blade vibrates at substantially the same frequency of the alternating field, thereby generating the air flow. GE's DCJ device is suitable for compact devices, mainly as a stand-alone device that blows air into surrounding electronic components from various angles.
FIG. 1 is a side view of a piezoelectric device, illustrating the expansion and compression of conventional piezoelectric device 170 (e.g., a DCJ device). The jets in a DCJ device were originally developed for controlling air flows around aerodynamic structures, so as to improve aerodynamic performance. Piezoelectric device 170 includes piezoelectric elements 200 that are separated by an elastomer. When a sinusoidal voltage is applied to the piezoelectric elements 200, piezoelectric elements 200 cause expansion and compression of piezoelectric device 170 through the elastomer, thereby allowing fluid to enter and exit piezoelectric device 170 through orifice or opening 180. The expansion and compression result in a strong fluid jet entering and exiting opening 180, even creating vortices that entrain additional fluid downstream of the DCJ device. The fluid jet helps remove heat from heat source 400 (e.g., electronic systems in the vicinity, such as avionics boxes). The result improves avionics computing. However, the DCJ device operates as an independent unit that blows air into heat source 400 only at certain angles, which is not easily adapted to a space-constrained device and impedes properly angling the DCJ device. The DCJ device is not designed to remove heat from heat source 400 quickly and to dissipate heat to a larger surface area.
The DCJ device is not integrated with other thermal modules to maximize heat extraction, dissipation, and cooling operations within the limited space.